How do I make dynamic 3D-printable hair?
Blender 2.80, add hair at a reduced count, comb it out, go to modifier then convert.
Then place the origin in a center point of the head. In edge, select all, "A". Now "E" for extrude, then "S" for scale, making face. Now in object mode add the modifier for solidify.

Takes some playing around. Maybe shrink a sphere to this. depends.
 Shrink works pretty good for body mesh expressions on Manuel Bastioni models. Nice clean, crisp slice, I always delete behind the eyes and internal mouth.